JP3928657B2 - Solder paste - Google Patents
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- JP3928657B2 JP3928657B2 JP2005518736A JP2005518736A JP3928657B2 JP 3928657 B2 JP3928657 B2 JP 3928657B2 JP 2005518736 A JP2005518736 A JP 2005518736A JP 2005518736 A JP2005518736 A JP 2005518736A JP 3928657 B2 JP3928657 B2 JP 3928657B2
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistors
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3465—Application of solder
- H05K3/3485—Application of solder paste, slurry or powder
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400°C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering or brazing
- B23K35/0244—Powders, particles or spheres; Preforms made therefrom
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering or brazing
- B23K35/0244—Powders, particles or spheres; Preforms made therefrom
- B23K35/025—Pastes, creams or slurries
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400°C
- B23K35/262—Sn as the principal constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C13/00—Alloys based on tin
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
- H05K2201/0203—Fillers and particles
- H05K2201/0263—Details about a collection of particles
- H05K2201/0272—Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistors
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by soldering
- H05K3/346—Solder materials or compositions specially adapted therefor
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Description
本発明はプリント基板と電子部品のはんだ付けに用いるソルダペ−スト、特にＳｎ−Ａｇ−Ｉｎ系の鉛フリ−はんだ合金を含むソルダペ−ストに関する。 The present invention relates to a solder paste used for soldering a printed circuit board and an electronic component, and more particularly to a solder paste containing a Sn-Ag-In based lead-free solder alloy.
抵抗やコンデンサ−等の単一機能の電子部品は、本体の両端に電極が形成されたチップ部品となっており、このような表面実装部品（Ｓｕｒｆａｃｅ Ｍｏｕｎｔｅｄ Ｄｅｖｉｃｅ：ＳＭＤ）をプリント基板にはんだ付けする場合は、リフロ−法で行なう。このリフロ−法とは、プリント基板のはんだ付け部、即ちＳＭＤの電極に一致する箇所にはんだ合金粉末とペースト状フラックスからなるソルダペ−ストを印刷や吐出により塗布し、その後、該プリント基板をリフロ−炉で加熱してはんだ合金粉末を溶融させることによりプリント基板と表面実装電子部品のはんだ付けを行なうものである。
このリフロー法では、加熱時にペースト状フラックスの突沸を防ぐと同時に、電子部品やプリント基板への熱影響を少なくするために１００〜１５０℃で予備加熱を行ない、その後、ソルダペースト中のはんだ合金粉末を溶融させてはんだ付け部に付着させる本加熱を行なう。本加熱では最高温度となるピーク温度をできるだけ低くし、その温度での加熱時間をなるべく短くして電子部品への熱影響を少なくするようにしている。
この本加熱温度は、プリント基板の大きさ、厚さ、電子部品の実装密度等によって適宜調整するが、当然ソルダペ−ストに用いるはんだ合金粉末を完全に溶融させるために、はんだ合金粉末の液相線温度以上となる。従って、ソルダペ−ストに用いるはんだ合金粉末は、液相線温度がなるべく低い方が本加熱温度も低くなり、それだけ電子部品に対する熱影響も少なくできる。一般に本加熱温度は、ソルダペ−ストに用いるはんだ合金の液相線温度＋２０〜４０℃といわれている。
ここに、最近では、鉛を全く含まない鉛フリ−はんだを使用することが推奨されており、ソルダペーストにも鉛フリ−はんだ合金が用いられるようになってきている。
鉛フリ−はんだは、Ｓｎを主成分として、用途に応じこれにＡｇ、Ｃｕ、Ｂｉ、Ｓｂ、Ｚｎ等を適宜添加したはんだ合金である。
Ｓｎ−Ｃｕ系鉛フリーはんだ合金は、Ｓｎ−０．７Ｃｕの共晶組成の融点が２２７℃であるため、本加熱温度が高くなってリフロ−時に電子部品を熱損傷させる。しかも、はんだ付け性が良好でないという問題があった。
Ｓｎ−Ｂｉ系鉛フリーはんだ合金は、Ｓｎ−５７Ｂｉの共晶組成の融点が１３９℃という低い温度であり、本加熱温度が従来のＳｎ−Ｐｂ共晶はんだよりもさらに低い温度であるため、リフロ−時の電子部品への熱損傷の心配は全くない。しかしながら、かかる組成の鉛フリ−はんだは、Ｂｉが大量に含有されているため非常に脆い性質を有しており、はんだ付け後、はんだ付け部に多少の衝撃が加わっただけで容易に剥離するという問題があった。
Ｓｎ−Ｚｎ系鉛フリーはんだ合金は、Ｓｎ−９Ｚｎの共晶組成の融点が１９９℃であり、本加熱温度が２３０℃以下となるため、リフロ−時の熱損傷は少ない。しかしＺｎは酸化しやすく、ぬれ性が極端に悪いという欠点があり、非酸化雰囲気中でリフローをおこなうか、特殊なフラックスを使用する必要があった。
Ｓｎ−Ａｇ系鉛フリーはんだ合金は、ぬれ性が良いためすでに多く使用されている。特にＳｎ−Ａｇはんだ合金に１％以下のＣｕを添加したＳｎ−Ａｇ−Ｃｕ鉛フリーはんだ合金は、Ｓｎ−Ａｇはんだ合金よりぬれ性が良く、はんだ合金の強度も強いため、現在最も多く使用されている。
しかし、Ｓｎ−Ａｇ系鉛フリーはんだ合金は、Ｓｎ−３．５Ａｇの共晶組成の融点が２２０℃であるため、本加熱温度は２５０℃以上となって熱に弱い電子部品には熱損傷を与えてしまう。
一方、Ｓｎ−Ａｇ−Ｃｕ鉛フリーはんだ合金の溶融温度は、約２１８℃であり、リフロー炉の本加熱設定温度は２４０℃前後の場合が多い。一般的なＳＭＤ部品の場合は、２４０℃前後の本加熱温度の使用でも熱による破損を受けることは少ないが、半導体やコネクター、電解コンデンサーなどの熱に弱い部品は熱による損傷を受けて、動作不良になる可能性がある。
そこで、Ｓｎ−Ａｇはんだ合金およびＳｎ−Ａｇ−Ｃｕはんだ合金に溶融温度を下げる合金としてＢｉやＩｎなどの元素を添加して、はんだ合金の溶融温度を下げた鉛フリーはんだ合金が提案されている。Ｂｉの添加ははんだ合金の強度を低下させることもあるので、Ｉｎを添加したＳｎ−Ａｇ−Ｉｎ系はんだ合金が耐熱性のない電子部品のはんだ付けに広く用いられている。
ここで、Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金とは、Ｓｎ、Ａｇ、Ｉｎからなる鉛フリーはんだ合金、もしくは、このはんだ合金にさらにＢｉ、Ｃｕ等の添加元素を加えたはんだ合金である。
ところで、電子機器の小型化に伴い電子部品も１６０８サイズ（１６ｍｍ×８ｍｍ）や１００５サイズ（１０ｍｍ×５ｍｍ）などと云うように小型化している。これらの小型の電子部品をソルダペーストを用いてリフローはんだ付けを行うと、電子部品が軽いためにリフロー後にチップ立ちやチップの傾きなどが発生しやすい。これらのリフロー後のチップ立ちやチップの傾きをツームストーン現象やマンハッタン現象と呼ぶこともある。
チップ立ち現象は、ソルダペーストを印刷した基板がリフロー炉で加熱されるときに、チップ部品の両端に置かれたソルダペーストに加熱の時間差が発生することにより両端でソルダペーストの溶解に時間差が生まれ、チップ部品が片側に引っ張られるモーメントが生じてチップ部品が浮く現象である。発生したモーメントが大きくなると、チップが完全に逆立ちしてしまう。
チップ立ち現象は、チップ部品が片側に引っ張られるモーメントが大きくなるほど顕著に現れるので、Ｓｎ−３７ＰｂはんだやＳｎ−３．５Ａｇなどのように共晶はんだと呼ばれる、固相線温度と液相線温度に差がないはんだ合金の組成ほど発生し易い。それに対して、Ｓｎ−２Ａｇ−３６Ｐｂ（固相線温度１７８℃−液相線温度２１０℃）、Ｓｎ−８Ｂｉ−４６Ｐｂ（同じく１５９℃−１９３℃）やＳｎ−ＩＡｇ−０．５Ｃｕ（同じく２１７℃−２２７℃℃）など固相線温度と液相線温度とが離れているはんだ合金では、はんだ合金の溶融が徐々におこなわれるので、チップ部品が片側に引っ張られるモ−メントが緩和され、チップ立ち現象が発生しにくくなる。現在最も広く用いられている鉛フリーはんだ合金のＳｎ−３Ａｇ−０．５Ｃｕ鉛フリーはんだ合金の溶融温度は、固相線温度２１７℃、液相線温度２２０℃で少しの温度差がある。そのためＳｎ−３７Ｐｂ組成の錫−鉛共晶はんだ合金の場合に比較して、リフロー時のチップ立ち現象は少なくなる。
しかしながら、前述のＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金においてはチップ立ち現象が特に顕著に表れ、電子部品への熱損傷が少ないというメリットを十分に活用していない。
従来にあっても、リフロー後のチップ立ちを防ぐ方法として、ツインピークが現れるはんだ合金組成を使用するものが提案されている（特開２００１−５８２８６号公報）。
一方、合金組成の異なる２種類以上のはんだ合金粉末を混合することは、従来から実施されてきた。鉛フリーはんだ合金においても、Ｓｎ−Ｚｎ系粉末とＳｎ−Ｚｎ−Ｂｉ系粉末を混合してぬれ性を改善すること（特開平９−２７７０８２号公報）、Ｓｎ−Ｂｉ系粉末とＳｎ−Ｚｎ系粉末を混合してボイドやディウエットを発生させないようにすること（特開２００２−１１３５９０号公報）がそれぞれ公知である。Single-function electronic components such as resistors and capacitors are chip components in which electrodes are formed at both ends of the main body, and such surface-mounted components (SMD) are soldered to a printed circuit board. In this case, the reflow method is used. In this reflow method, a solder paste made of solder alloy powder and paste-like flux is applied to a soldered portion of a printed circuit board, that is, a portion corresponding to an SMD electrode by printing or discharging, and then the printed circuit board is reflowed. -Soldering of a printed circuit board and a surface mount electronic component by melting in a solder alloy powder by heating in a furnace.
In this reflow method, preheating is performed at 100 to 150 ° C. to prevent bumping of the paste-like flux during heating and at the same time to reduce the heat effect on the electronic component and the printed circuit board, and then the solder alloy powder in the solder paste The main heating is performed to melt and adhere to the soldering part. In the main heating, the peak temperature, which is the maximum temperature, is made as low as possible, and the heating time at that temperature is shortened as much as possible to reduce the heat influence on the electronic component.
This heating temperature is appropriately adjusted according to the size, thickness, and mounting density of electronic components of the printed circuit board. Naturally, in order to completely melt the solder alloy powder used for the solder paste, the liquid phase of the solder alloy powder is used. Above the line temperature. Therefore, the solder alloy powder used for the solder paste has a lower liquidus temperature as much as possible, so that the main heating temperature becomes lower, and the thermal influence on the electronic component can be reduced accordingly. Generally, this heating temperature is said to be the liquidus temperature of the solder alloy used for the solder paste + 20 to 40 ° C.
Recently, it has been recommended to use lead-free solder containing no lead at all, and lead-free solder alloys have been used for solder paste.
The lead-free solder is a solder alloy in which Sn is a main component and Ag, Cu, Bi, Sb, Zn or the like is appropriately added depending on the application.
Since the melting point of the Sn—0.7Cu eutectic composition is 227 ° C., the Sn—Cu-based lead-free solder alloy increases the main heating temperature and causes thermal damage to the electronic components during reflow. Moreover, there is a problem that solderability is not good.
The Sn-Bi lead-free solder alloy has a low melting point of 139 ° C of the eutectic composition of Sn-57Bi, and this heating temperature is even lower than the conventional Sn-Pb eutectic solder. -There is no worry of thermal damage to electronic components at times. However, the lead-free solder having such a composition has a very fragile property because it contains a large amount of Bi, and after soldering, it is easily peeled off only by applying a slight impact to the soldered portion. There was a problem.
The Sn—Zn-based lead-free solder alloy has a melting point of the eutectic composition of Sn-9Zn of 199 ° C. and the main heating temperature is 230 ° C. or less, so there is little thermal damage during reflow. However, Zn has the disadvantages that it is easily oxidized and its wettability is extremely poor, and it has been necessary to reflow in a non-oxidizing atmosphere or to use a special flux.
Sn-Ag-based lead-free solder alloys are already widely used because of their good wettability. In particular, Sn-Ag-Cu lead-free solder alloy with 1% or less of Cu added to Sn-Ag solder alloy has better wettability than Sn-Ag solder alloy, and the strength of solder alloy is higher, so it is most frequently used at present. ing.
However, the Sn-Ag lead-free solder alloy has an eutectic composition of Sn-3.5Ag with a melting point of 220 ° C, so that the heating temperature is 250 ° C or higher, and heat-sensitive electronic components are not damaged. I will give it.
On the other hand, the melting temperature of the Sn—Ag—Cu lead-free solder alloy is about 218 ° C., and the main heating set temperature of the reflow furnace is often around 240 ° C. In the case of general SMD parts, even if the main heating temperature of around 240 ° C is used, it is rarely damaged by heat, but heat-sensitive parts such as semiconductors, connectors and electrolytic capacitors are damaged by heat and operate. It may become defective.
Therefore, lead-free solder alloys have been proposed in which elements such as Bi and In are added to Sn—Ag solder alloys and Sn—Ag—Cu solder alloys to lower the melting temperature to lower the melting temperature of the solder alloy. . Since the addition of Bi may reduce the strength of the solder alloy, the Sn—Ag—In based solder alloy to which In is added is widely used for soldering electronic components having no heat resistance.
Here, the Sn—Ag—In-based lead-free solder alloy is a lead-free solder alloy made of Sn, Ag, or In, or a solder alloy obtained by adding an additive element such as Bi or Cu to the solder alloy.
By the way, with the miniaturization of electronic devices, electronic components are also miniaturized such as 1608 size (16 mm × 8 mm) and 1005 size (10 mm × 5 mm). When these small electronic components are reflow soldered using a solder paste, the electronic components are light, and thus chip standing and tip tilting are likely to occur after reflow. These chip standing and chip inclination after reflow are sometimes called tombstone phenomenon or Manhattan phenomenon.
As for the chip standing phenomenon, when the solder paste printed board is heated in a reflow oven, a time difference in heating occurs in the solder paste placed at both ends of the chip component, resulting in a time difference in melting of the solder paste at both ends. This is a phenomenon that the chip component floats due to the moment that the chip component is pulled to one side. When the moment generated is large, the tip is completely upside down.
The chip standing phenomenon becomes more prominent as the moment at which the chip component is pulled to one side increases. Therefore, the solidus temperature and the liquidus temperature called eutectic solder such as Sn-37Pb solder and Sn-3.5Ag are used. It is more likely to occur as the composition of the solder alloy with no difference between the two. In contrast, Sn-2Ag-36Pb (solidus temperature 178 ° C.-liquidus temperature 210 ° C.), Sn-8Bi-46Pb (also 159 ° C.-193 ° C.) and Sn-IAg-0.5Cu (also 217 ° C.). In the case of a solder alloy in which the solidus temperature and the liquidus temperature are different, such as −227 ° C., the melting of the solder alloy is gradually performed. Standing phenomenon is less likely to occur. The melting temperature of the Sn-3Ag-0.5Cu lead-free solder alloy, which is currently the most widely used lead-free solder alloy, has a slight temperature difference between a solidus temperature of 217 ° C and a liquidus temperature of 220 ° C. Therefore, the chip standing phenomenon during reflow is reduced as compared with the case of a tin-lead eutectic solder alloy having a Sn-37Pb composition.
However, the above-described Sn—Ag—In-based lead-free solder alloy exhibits a particularly noticeable chip standing phenomenon and does not fully utilize the merit that thermal damage to electronic components is small.
Even in the past, as a method for preventing chip standing after reflow, a method using a solder alloy composition in which a twin peak appears has been proposed (Japanese Patent Laid-Open No. 2001-58286).
On the other hand, mixing two or more kinds of solder alloy powders having different alloy compositions has been conventionally performed. Also in a lead-free solder alloy, Sn-Zn-based powder and Sn-Zn-Bi-based powder are mixed to improve wettability (Japanese Patent Laid-Open No. 9-277082), Sn-Bi-based powder and Sn-Zn-based powder It is publicly known that powders are mixed to prevent generation of voids and dewetting (Japanese Patent Laid-Open No. 2002-113590).
本発明は、リフロー後のチップ立ちが発生しやすいＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金を使っても、チップ立ちの起こりにくいＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金のソルダペーストを提供することである。
Ｓｎ−３．５Ａｇ鉛フリーはんだ合金やＳｎ−３Ａｇ−０．５Ｃｕ鉛フリーはんだ合金に、溶融温度を下げる元素であるＩｎやＢｉなどを添加すると、はんだの溶融温度が下がってくる。このとき固相線温度と液相線温度が単純に下がるのではなく、固相線温度は下がるが、液相線温度は必ずしも下がらず、固相線温度と液相線温度の差が広まっていく傾向にある。そのためＩｎやＢｉなどを添加したはんだ合金は、リフロー時のチップ立ち現象が少なくなるはずである。ところが、Ｂｉを添加する場合はリフロー時のチップ立ち現象は少なくなるが、Ｉｎを添加すると逆にリフロー時のチップ立ち現象が多く起こる。
例えば、Ｓｎ−３．５Ａｇ−８Ｉｎ（固相線温度１９７℃−液相線温度２１４℃）の鉛フリーはんだ合金は、Ｓｎ−３Ａｇ−０．５Ｃｕ鉛フリーはんだ合金に比較して２０倍以上多くリフロー時のチップ立ち現象が発生してしまう。それに対して、Ｓｎ−３．５Ａｇ−８Ｂｉ（固相線温度１８６℃−液相線温度２０７℃）鉛フリーはんだ合金は、Ｓｎ−３Ａｇ−０．５Ｃｕ鉛フリーはんだ合金に比較して半減する。Ｉｎを添加するとはんだ合金の表面張力が下がりぬれ性が良くなる反面、酸化しやすい元素でもあることからはんだの溶融を阻害する面もある。このため、ぬれにバラツキが生じ、チップ立ちが発生する。
すなわち、チップ立ちの防止には単に液相線温度と固相線温度との領域を十分に広く確保することでだけでは十分でないことが分かる。
一方、同じように鉛フリーはんだ合金の溶融温度を低下させる元素としてＺｎがある。Ｚｎを添加しても固相温度は大きく下がらないが、Ｚｎを添加するとはんだ合金のぬれ性が極端に悪くなるのでチップ部品へのモーメントが急に働かず、Ｚｎが添加された鉛フリーはんだ合金はリフロー時のチップ立ち現象が少ない。
このように、はんだ合金組成によってチップ立ち防止の機構は大きく異なるのであって、したがって、特定のはんだ合金で有効が手段がそのまま別のはんだ合金においても有効であるか否かは予測がつかないのである。
実際、リフロー時のチップ立ち現象の対策として、溶融温度の違う２種類の粉末を使用する方法がある。ところがＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金では、単に溶融温度の違う２種類の粉末を混合してソルダペーストにしただけでは、チップ立ち現象は低減しない。Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金自体のぬれ性は良いのだが、Ｉｎが酸化し易いためである。
本発明者らは、Ａｇ：３〜４％、Ｉｎ：３〜１０％、残部ＳｎのＳｎ−Ａｇ−Ｉｎ鉛フリーはんだ合金において、その合金組成を第一合金粉末と第二合金粉末に分割することで、第一合金粉末のはんだ合金と第二合金粉末のはんだ合金の示差熱分析（ＤＳＣ）で測定したピーク温度の差が１０℃以上あるはんだ合金の粉末の組み合わせが存在すること、そして、それらを混合してなるソルダペーストを用いると、特に、Ｓｎ−Ａｇ−Ｉｎの第一はんだ合金粉末とＳｎ−Ａｇの第二はんだ合金粉末を混合した粉末を用いてソルダペーストを構成すると、チップ立ちが減少することを見出し、本発明を完成させた。
すなわち、単に融点の異なる２種のはんだ合金を用いるのとは異なって、第一はんだ合金粉末と温度の高い第二はんだ合金粉末のピーク温度の差を１０℃以上とすることによって、Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金でもリフロー時に発生するモーメントを小さくすることができ、しかも、溶融後の組成を、質量％で、Ａｇ：３〜４％、Ｉｎ：３〜１０、残部ＳｎとなるようにすることによりＩｎの酸化を起きにくくすることによりチップ立ちを効果的に防止することができる。好ましくはピーク温度の低いほうのはんだ合金粉末に合金成分としてＩｎを配合しておくことによりＩｎの酸化を可及的少とすれば、Ｉｎが酸化し易いために発生するモーメントをさらに緩和することができ、リフロー時のチップ立ちを一層減少させることができる。これはＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金に特有の作用効果と云える。
本発明は、第一はんだ合金粉末と第二はんだ合金粉末とを混合した混合粉末とフラックスとからなるソルダペーストにおいて、第一はんだ合金粉末と第二はんだ合金粉末とは、示差熱分析で測定したメインのピーク温度の差が１０℃以上であり、しかも混合粉末の溶融後の組成が、質量％で、Ａｇ：３〜４％、Ｉｎ：３〜１０％、残部Ｓｎとなることを特徴とするソルダペーストである。
本明細書において、合金組成を示す「％」は、特にことわりがない限り、「質量％」である。
好ましくは、第一はんだ合金粉末は、Ａｇ：３〜４％、Ｉｎ：６〜２０％、残部Ｓｎからなる合金の粉末であり、第二はんだ合金粉末は、Ａｇ：３〜４％、残部Ｓｎからなる合金の粉末である。
第一、第二はんだ合金粉末の合金には、いずれか一方、または両方に１％以下のＢｉを配合してもよい。あるいは、ピーク温度の高い第二はんだ合金粉末の合金には、１％以下のＣｕを配合してもよい。The present invention provides a solder paste of an Sn-Ag-In lead-free solder alloy in which chip standing does not easily occur even when a Sn-Ag-In lead-free solder alloy that easily causes chip standing after reflow is used. It is.
When In, Bi or the like, which is an element that lowers the melting temperature, is added to Sn-3.5Ag lead-free solder alloy or Sn-3Ag-0.5Cu lead-free solder alloy, the melting temperature of the solder is lowered. At this time, the solidus temperature and the liquidus temperature are not simply lowered, but the solidus temperature is lowered, but the liquidus temperature is not necessarily lowered, and the difference between the solidus temperature and the liquidus temperature is widened. It tends to go. Therefore, a solder alloy to which In or Bi is added should reduce the chip standing phenomenon during reflow. However, when Bi is added, the chip standing phenomenon during reflow is reduced. However, when In is added, many chip standing phenomena during reflow occur.
For example, the lead-free solder alloy of Sn-3.5Ag-8In (solidus temperature 197 ° C.-liquidus temperature 214 ° C.) is 20 times more than Sn-3Ag-0.5Cu lead-free solder alloy Chip standing phenomenon during reflow occurs. In contrast, Sn-3.5Ag-8Bi (solidus temperature 186 ° C.−liquidus temperature 207 ° C.) lead-free solder alloy is halved compared to Sn-3Ag-0.5Cu lead-free solder alloy. When In is added, the surface tension of the solder alloy is lowered and the wettability is improved. On the other hand, since it is an element that is easily oxidized, there is also a surface that hinders melting of the solder. For this reason, variation occurs in wetting and chip standing occurs.
That is, it can be seen that it is not sufficient to prevent the chip standing by simply ensuring a sufficiently wide area between the liquidus temperature and the solidus temperature.
On the other hand, there is Zn as an element that similarly lowers the melting temperature of the lead-free solder alloy. Even if Zn is added, the solid phase temperature does not drop greatly. However, if Zn is added, the wettability of the solder alloy becomes extremely poor. Has less chip standing phenomenon during reflow.
As described above, the mechanism for preventing chip standing varies greatly depending on the solder alloy composition. Therefore, it is unpredictable whether a specific solder alloy is effective in other solder alloys. is there.
Actually, there is a method of using two types of powders having different melting temperatures as a countermeasure against the chip standing phenomenon during reflow. However, in the Sn-Ag-In lead-free solder alloy, the chip standing phenomenon is not reduced simply by mixing two kinds of powders having different melting temperatures into a solder paste. This is because the Sn-Ag-In lead-free solder alloy itself has good wettability, but In is easily oxidized.
In the Sn-Ag-In lead-free solder alloy of Ag: 3 to 4%, In: 3 to 10%, and the remaining Sn, the inventors divide the alloy composition into a first alloy powder and a second alloy powder. Thus, there exists a combination of solder alloy powders having a difference in peak temperature measured by differential thermal analysis (DSC) between the solder alloy of the first alloy powder and the solder alloy of the second alloy powder of 10 ° C. or more, and When a solder paste formed by mixing them is used, particularly when the solder paste is constituted by using a powder obtained by mixing a first solder alloy powder of Sn-Ag-In and a second solder alloy powder of Sn-Ag, a chip standing is caused. And the present invention was completed.
That is, unlike the case of simply using two types of solder alloys having different melting points, the difference in peak temperature between the first solder alloy powder and the high temperature second solder alloy powder is set to 10 ° C. or higher. -In-based lead-free solder alloy can also reduce the moment generated during reflow, and the composition after melting can be Ag: 3-4%, In: 3-10, and remaining Sn in mass%. By making it difficult to cause the oxidation of In, chip standing can be effectively prevented. Preferably, by mixing In as an alloy component in the solder alloy powder having the lower peak temperature, if the oxidation of In is made as small as possible, the moment generated because In is easily oxidized can be further reduced. As a result, chip standing during reflow can be further reduced. This can be said to be a function and effect peculiar to the Sn—Ag—In based lead-free solder alloy.
The present invention is a solder paste comprising a mixed powder obtained by mixing a first solder alloy powder and a second solder alloy powder and a flux, and the first solder alloy powder and the second solder alloy powder are measured by differential thermal analysis. The difference in main peak temperature is 10 ° C. or more, and the composition of the mixed powder after melting is Ag: 3 to 4%, In: 3 to 10%, and the balance Sn. Solder paste.
In this specification, “%” indicating the alloy composition is “% by mass” unless otherwise specified.
Preferably, the first solder alloy powder is an alloy powder composed of Ag: 3 to 4%, In: 6 to 20%, and the balance Sn, and the second solder alloy powder is Ag: 3 to 4% and the balance Sn. An alloy powder consisting of
The alloy of the first and second solder alloy powders may contain 1% or less of Bi in either or both. Or you may mix | blend 1% or less of Cu with the alloy of the 2nd solder alloy powder with a high peak temperature.
図１は、代表的な示差熱分析曲線を示すグラフである。
図２は、別の例の示差熱分析曲線を示すグラフである。
図３は、実施例において使用した第一はんだ合金粉末と第二はんだ合金粉末との混合粉末の示差熱分析曲線を示すグラフである。
発明の具体的な説明
Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金で、示差熱分析で測定した第一はんだ合金粉末と第二はんだ合金粉末のピーク温度の差が１０℃以上あるはんだ合金の粉末の組み合わせの具体的例は後述する実施例に記載した表１の通りである。
本発明において、ピーク温度の測定は、下記装置を使って示差熱分析により行った。
測定条件 測定装置：セイコーインスツルメント製示差走査熱量計
昇温速度：５℃／ｍｉｎ
図１は、代表的な示差熱分析曲線を示すが、これは明瞭な単一ピーク温度Ｐを示す合金の例であり、図中、Ｂ点の外挿点が固相線温度Ｓであり、図示例の場合、ピーク温度と溶融終了温度、つまり液相線温度とは同一となる。Ａ点は熱吸収開始点である。
図２は、ピーク温度Ｐと液相線温度Ｌとが異なる場合を示す示差熱分析曲線であり、この場合には液相線温度はピーク温度より高温側にある。
このように複数のピーク温度が見られるときはより大きな熱吸収のピーク温度、つまりメインのピーク温度をもって、本発明のピーク温度とする。
第一はんだ合金粉末と第二はんだ合金粉末のピーク温度の差が１０℃以上ある組み合わせでも、最終的に得られる組成のはんだ合金のぬれ性が悪いと濡れ不良やはんだボールの原因になってしまう。
したがって、本発明にあっては、最終組成のＳｎ−Ａｇ−Ｉｎ系はんだ合金において、Ａｇの量が３％未満ではぬれ性が低下し、Ａｇの量が４％を超えるとピーク温度が上がるため耐熱性の低い電子部品に適用できない。また、Ｉｎの量が３％未満ではピーク温度が下がらないため耐熱性の低い電子部品に適用できず、Ｉｎの量が１０％を超えると酸化しやすいＩｎの特性が顕著になり、ぬれ性が低下し、ボールの発生が多くなる。
本発明における第一、第二はんだ合金粉末の好ましい組み合わせの例は、ピーク温度の低い第一はんだ合金粉末が、Ａｇ：３〜４％、Ｉｎ：６〜２０％、残部ＳｎのＳｎ−Ａｇ−Ｉｎ合金のそれであり、ピーク温度の高い第二はんだ合金粉末が、Ａｇ：３〜４％、残部ＳｎのＳｎ−Ａｇ合金のそれである場合である。
本発明における第一はんだ合金粉末と、第二はんだ合金粉末との配合比率は、第一、第二はんだ合金粉末の組成によっても変わるが、一般には、高温ピーク温度の第一はんだ合金粉末／低温ピーク温度の第二はんだ合金粉末の比率（質量）は、（２０〜７０）／（８０〜３０）であり、好ましくは（２５〜６５）／（７５〜３５）である。
粉末の粒径については特に本発明においては制限されず、通常のソルダペーストに用いる程度のそれでよく、例えば、第一、第二はんだ合金粉末とも、平均粒径３０μｍの程度であればよい。もちろん、必要に応じて、これより粗いあるいは細かい粒径の粉末を用いてもよい。
さらに、フラックス成分としても、従来のＳｎ−Ａｇ−Ｉｎ系はんだ合金を使ったソルダペーストのそれに同じであってもよく、特に制限はなく、例えば、各種ロジン系フラックスおよび適宜溶剤を用いることができ、これに必要に応じて活性剤、チキソ剤、酸化防止剤等を適宜配合してもよい。
本発明の効果には、リフロー時のチップ立ち防止効果だけでなく、ボイド減少効果もある。これは、はんだ合金が溶融する時間に差が生じるためにソルダペーストに含まれている溶剤が急激に蒸発しないからである。
また、本発明の溶融後のはんだ合金組成が、Ａｇ：３〜４％、Ｉｎ：３〜１０％、残部Ｓｎの範囲では、本来酸化しやすいＩｎの酸化が起きにくく、Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金の中ではボイドが少なくなる特長がある。
本発明のＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金はぬれ性を向上させるために、その第一はんだ合金粉末および／または第二はんだ合金粉末にＢｉを１％以下添加することができる。Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金は、ぬれ性は良いがＩｎが酸化しやすい欠点がある。そこで、Ｓｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金にＢｉを添加することによって、ぬれ性を増してボイドの少ないはんだ接合を作ることが可能となる。ただし、溶融後のはんだ合金のＢｉの含有量が１％を超すと、はんだの強度低下やリフトオフ現象などが見られ、はんだ剥離を起こすようになる。そのため、第一はんだ合金粉末および／または第二はんだ合金粉末にＢｉを配合する場合、そのＢｉ添加量は合計で１％以下とする。
本発明は、したがって、その一つの態様では、第一はんだ合金粉末がＡｇ：３〜４％、Ｉｎ：６〜２０％、および残部Ｓｎからなる合金の粉末から、第二はんだ合金粉末がＡｇ：３〜４％、および残部Ｓｎからなる合金の粉末からなり、第一および／または第二はんだ合金粉末のはんだ合金が合計でＢｉ：１％以下を含有しており、これらのはんだ合金粉末を混合した粉末とフラックスとが混和されていることを特徴とするソルダペーストである。
また、本発明にあっては、第二はんだ合金粉末にＣｕを１％以下添加することができる。Ｃｕの添加が、１％より多くなると溶融温度が上昇し更にぬれが悪くなり、ボイドの原因になりやすい。この場合のＣｕは第二はんだ合金粉末に添加する。第二はんだ合金粉末にＣｕを添加することで、少しでも溶融温度を下げ、リフロー時に第一はんだ合金粉末と融合しやすくするためである。
したがって、本発明は、その別の態様においては、合金組成がＡｇ：３〜４％、Ｉｎ：６〜２０％および残部Ｓｎからなる第一はんだ合金粉末と、合金組成がＡｇ：３〜４％、Ｃｕ：１％以下および残部Ｓｎからなる第二はんだ合金粉末を混合した混合粉末とフラックスとが混和されていることを特徴とするソルダペーストである。
上記態様においてもさらにぬれ性を高めるためにＢｉを添加してもよい。
したがって、本発明は、さらに別の態様では、合金組成がＡｇ：３〜４％、Ｉｎ：６〜２０％、および残部Ｓｎからなるはんだ合金の第一はんだ合金粉末と、合金組成がＡｇ：３〜４％、Ｃｕ：１％以下および残部Ｓｎからなる第二はんだ合金粉末からなり、第一および／または第二はんだ合金粉末のはんだ合金が合計でＢｉ：１％以下を含有しており、これらのはんだ合金粉末とフラックスとが混和されていを混合した粉末とフラックスとが混和されていることを特徴とするソルダペーストである。
本発明にあっては、いずれの態様にあって、上記第一、第二はんだ合金粉末の溶融後の組成は、Ａｇ：３〜４％、Ｉｎ：３〜１０％およびＢｉ：０〜１％、Ｃｕ：０〜１％、残部Ｓｎとなる。
次に、実施例によって本発明の作用効果をさらに具体的に説明する。FIG. 1 is a graph showing a typical differential thermal analysis curve.
FIG. 2 is a graph showing a differential thermal analysis curve of another example.
FIG. 3 is a graph showing a differential thermal analysis curve of a mixed powder of the first solder alloy powder and the second solder alloy powder used in the examples.
DETAILED DESCRIPTION OF THE INVENTION A Sn-Ag-In lead-free solder alloy, a solder alloy powder having a difference in peak temperature between the first solder alloy powder and the second solder alloy powder measured by differential thermal analysis of 10 ° C. or more. Specific examples of the combinations are as shown in Table 1 described in Examples described later.
In the present invention, the peak temperature was measured by differential thermal analysis using the following apparatus.
Measurement conditions Measuring device: Seiko Instruments differential scanning calorimeter
Temperature increase rate: 5 ° C / min
FIG. 1 shows a representative differential thermal analysis curve, which is an example of an alloy showing a clear single peak temperature P, in which the extrapolated point of point B is the solidus temperature S, In the case of the illustrated example, the peak temperature and the melting end temperature, that is, the liquidus temperature are the same. Point A is a heat absorption start point.
FIG. 2 is a differential thermal analysis curve showing a case where the peak temperature P and the liquidus temperature L are different. In this case, the liquidus temperature is higher than the peak temperature.
When a plurality of peak temperatures are observed in this way, the peak temperature of the present invention is set to a larger peak temperature of heat absorption, that is, the main peak temperature.
Even in a combination where the difference in peak temperature between the first solder alloy powder and the second solder alloy powder is 10 ° C. or more, if the wettability of the solder alloy having the finally obtained composition is poor, it causes wet defects and solder balls. .
Therefore, in the present invention, in the Sn—Ag—In solder alloy having the final composition, the wettability decreases when the amount of Ag is less than 3%, and the peak temperature increases when the amount of Ag exceeds 4%. It cannot be applied to electronic parts with low heat resistance. In addition, if the amount of In is less than 3%, the peak temperature does not decrease, so it cannot be applied to electronic components with low heat resistance. Decreases and ball generation increases.
An example of a preferable combination of the first and second solder alloy powders in the present invention is that the first solder alloy powder having a low peak temperature is Ag: 3 to 4%, In: 6 to 20%, and the remaining Sn—Ag— This is a case where the second solder alloy powder having a high peak temperature is that of an In alloy and that of Ag: 3 to 4%, and the remaining Sn—Ag alloy.
The mixing ratio of the first solder alloy powder and the second solder alloy powder in the present invention varies depending on the composition of the first and second solder alloy powders. The ratio (mass) of the second solder alloy powder at the peak temperature is (20 to 70) / (80 to 30), preferably (25 to 65) / (75 to 35).
The particle size of the powder is not particularly limited in the present invention, and may be that used in a normal solder paste. For example, both the first and second solder alloy powders may have an average particle size of about 30 μm. Of course, if necessary, powder having a coarser or finer particle diameter may be used.
Further, the flux component may be the same as that of a solder paste using a conventional Sn-Ag-In solder alloy, and there is no particular limitation. For example, various rosin fluxes and appropriate solvents can be used. In addition, an activator, a thixotropic agent, an antioxidant, and the like may be appropriately blended as necessary.
The effects of the present invention include not only a chip standing prevention effect during reflow but also a void reduction effect. This is because the solvent contained in the solder paste does not evaporate rapidly because of the difference in the melting time of the solder alloy.
Further, in the case where the solder alloy composition after melting of the present invention is in the range of Ag: 3 to 4%, In: 3 to 10%, and the remaining Sn, the oxidation of In which is easily oxidized is unlikely to occur, and the Sn-Ag-In series Among lead-free solder alloys, there is a feature that voids are reduced.
In order to improve the wettability of the Sn—Ag—In based lead-free solder alloy of the present invention, 1% or less of Bi can be added to the first solder alloy powder and / or the second solder alloy powder. Sn-Ag-In-based lead-free solder alloys have good wettability, but have a defect that In is easily oxidized. Therefore, by adding Bi to the Sn—Ag—In-based lead-free solder alloy, it becomes possible to increase the wettability and make a solder joint with less voids. However, if the Bi content of the solder alloy after melting exceeds 1%, a decrease in solder strength, a lift-off phenomenon, and the like are observed, and solder peeling occurs. Therefore, when adding Bi to the first solder alloy powder and / or the second solder alloy powder, the amount of Bi added is set to 1% or less in total.
Therefore, the present invention, in one embodiment thereof, is obtained from an alloy powder in which the first solder alloy powder is made of Ag: 3 to 4%, In: 6 to 20%, and the remaining Sn, and the second solder alloy powder is made of Ag: It is composed of 3-4% and the balance Sn alloy powder, and the first and / or second solder alloy powder contains a total of Bi: 1% or less, and these solder alloy powders are mixed. The solder paste is characterized in that the powder and the flux are mixed.
In the present invention, 1% or less of Cu can be added to the second solder alloy powder. If the addition of Cu is more than 1%, the melting temperature rises and the wetting becomes worse, which tends to cause voids. In this case, Cu is added to the second solder alloy powder. This is because by adding Cu to the second solder alloy powder, the melting temperature is lowered as much as possible to facilitate fusion with the first solder alloy powder during reflow.
Accordingly, in another aspect of the present invention, the first solder alloy powder having an alloy composition of Ag: 3 to 4%, In: 6 to 20% and the balance Sn, and the alloy composition of Ag: 3 to 4% The solder paste is characterized in that a mixed powder obtained by mixing the second solder alloy powder composed of Cu: 1% or less and the balance Sn and a flux are mixed.
In the above embodiment, Bi may be added to further improve the wettability.
Therefore, in yet another aspect of the present invention, a first solder alloy powder of a solder alloy having an alloy composition of Ag: 3 to 4%, In: 6 to 20%, and the balance Sn, and an alloy composition of Ag: 3 -4%, Cu: 1% or less and the second solder alloy powder consisting of the remainder Sn, the solder alloy of the first and / or second solder alloy powder contains Bi: 1% or less in total, these The solder paste is characterized in that the solder alloy powder and the flux are mixed and the powder and the flux are mixed.
In the present invention, in any embodiment, the composition of the first and second solder alloy powders after melting is as follows: Ag: 3 to 4%, In: 3 to 10%, and Bi: 0 to 1% Cu: 0 to 1%, remaining Sn.
Next, the effects of the present invention will be described more specifically with reference to examples.
表１に示した合金組成および割合の第一はんだ合金粉末および第二はんだ合金粉末（平均粒径はそれぞれ３０μｍ）を混合し、次の組成のフラックスと混和してソルダペーストを得た。このときのはんだ粉末とフラックスの比率は、混合したはんだ合金粉末８９％、フラックス１１％であった。
（フラックス組成）
アクリル変性ロジン ３０質量％
重合ロジン ２０質量％
硬化ヒマシ油 ５質量％
２エチルヘキシルジグリコール ４０質量％
２・３−ジブロモ ２−ブテン−１・４−ジオール ５質量％
作製したソルダペーストに対して、以下の試験方法でチップ立ち試験、ボイドの確認試験およびソルダボール試験を実施した。
（チップ立ち試験）
プリント基板に実施例および比較例のソルダペーストを下記配置となるように印刷し、そこに１００５サイズのチップコンデンサーを９０個搭載した。次いで、基板を反転させ、逆さにしてリフロー処理を行った後に見られるチップ立ちおよびその定位置を外れた部品の数をカウントした。いずれの場合にもはんだ付け不良であって、本例ではそれらの欠陥を合計した数をもってチップ立ち発生率を計算している。（ｎ＝３）
印刷形状 ： ０．５ｍｍ（ドット直径）
印刷ピッチ ： １．０ｍｍ
メタルマスク厚： ０．１５ｍｍ
（ボイドの確認試験）
プリント基板に実施例および比較例のソルダペーストを下記配置となるように印刷し、部品を搭載せずリフローを行った。ボイドの大きさがランド径の半分以上の大きさを持った
ボイドが発生したランドの数をカウントした。（ｎ＝３）
ドット数 ： ３６個
印刷形状 ： ０．５ｍｍ（ドット直径）
印刷ピッチ ： １．０ｍｍ
メタルマスク厚： ０．１５ｍｍ
（ソルダボール試験）
実施例および比較例のソルダペーストを用いて、ＪＩＳ Ｚ３２８４付属書１１の条件でソルダボール試験を行い、そのソルダボールの状態をカテゴリー別に判定した。
ここに、カテゴリ１は、ソルダボールがない状態、カテゴリ２は、直径７５μｍ以下のソルダボールが３つ以下ある状態、同じく３は、同じく４つ以上ある状態、４は多数の細かいソルダボールが半連続で環状に並んでいる状態である。カテゴリ２までが合格である。
（リフロー条件）
本例におけるチップ立ち試験、ボイドの確認試験およびはんだボール試験でのリフローは次の条件で行った。
リフロー炉 ： 千住金属工業製 ＳＡＩ−３８０８ＪＣ
プリヒート温度 ： １５０〜１７０℃ １００秒
本加熱温度 ： ２２０℃（ただし、２００℃以上４０秒）
結果は表１にまとめて示すが、これらの結果からも分かるように、本発明のＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金で、示差熱分析で測定した第一はんだ合金粉末と第二はんだ合金粉末のピーク温度の差が１０℃以上のあるはんだ合金の粉末の組み合わせにより作製したソルダペーストは、合金ピーク温度の差が１０℃未満のものに比較して、チップ立ちおよびボイドの発生が少なく、またソルダボールも少ない。
図３は、第一はんだ合金粉末（Ｓｎ−３．５Ａｇ−１２Ｉｎ−０．５Ｂｉ）６５％と第二はんだ合金粉末（Ｓｎ−３．５Ａｇ−０．５Ｂｉ）３５％とを混合したはんだ合金混合粉末の示差熱分析曲線を示すグラフであるが、第一はんだ合金粉末と第二はんだ合金粉末の各ピーク温度Ｐ１、Ｐ２が１０℃以上と十分に離れているため、実際には第一はんだ合金粉末の液相線温度と第二はんだ合金粉末の固相線温度が重なることはない。むしろそのようになるように、ピーク温度の差が１０℃以上となる第一、第二はんだ合金粉末を選択し、組み合わせてソルダペーストを構成するのである。溶融後の組成はＳｎ−３．５Ａｇ−８Ｉｎ−０．５Ｂｉであった。
云うまでもなく、本発明のＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金は、チップ部品のはんだ付けばかりでなく、微細なパターンのはんだ付けにも効果をもたらすものである。
(Flux composition)
Acrylic modified rosin 30% by mass
Polymerized rosin 20% by mass
Hardened castor oil 5% by mass
2-ethylhexyl diglycol 40% by mass
2,3-dibromo 2-butene-1,4-diol 5% by mass
The produced solder paste was subjected to a chip standing test, a void confirmation test, and a solder ball test by the following test methods.
(Chip standing test)
The solder pastes of Examples and Comparative Examples were printed on a printed circuit board so as to have the following arrangement, and 90 1005-size chip capacitors were mounted thereon. Next, the number of the chip standing and the number of components out of its fixed position, which were seen after the reflow process was performed by turning the substrate upside down, was counted. In any case, it is a soldering failure, and in this example, the chip standing rate is calculated by the total number of these defects. (N = 3)
Print shape: 0.5mm (Dot diameter)
Printing pitch: 1.0mm
Metal mask thickness: 0.15mm
(Void confirmation test)
The solder pastes of Examples and Comparative Examples were printed on a printed circuit board so as to have the following arrangement, and reflow was performed without mounting components. The number of lands in which voids with a void size more than half the land diameter occurred was counted. (N = 3)
Number of dots: 36 Print shape: 0.5 mm (dot diameter)
Printing pitch: 1.0mm
Metal mask thickness: 0.15mm
(Solder ball test)
Using the solder pastes of Examples and Comparative Examples, a solder ball test was performed under the conditions of JIS Z3284 Appendix 11, and the state of the solder balls was determined by category.
Here, category 1 is a state where there is no solder ball, category 2 is a state where there are 3 or less solder balls having a diameter of 75 μm or less, 3 is a state where there are also 4 or more solder balls, and 4 is a half where many fine solder balls are half. It is in a state of being continuously arranged in a ring. Up to category 2 is acceptable.
(Reflow conditions)
The chip standing test, void confirmation test, and solder ball test in this example were performed under the following conditions.
Reflow furnace: SAI-3808JC manufactured by Senju Metal Industry
Preheating temperature: 150 to 170 ° C. 100 seconds Main heating temperature: 220 ° C. (however, 200 ° C. or more and 40 seconds)
The results are summarized in Table 1. As can be seen from these results, the Sn-Ag-In lead-free solder alloy of the present invention, the first solder alloy powder and the second solder alloy measured by differential thermal analysis. Solder paste produced by a combination of solder alloy powders having a difference in powder peak temperature of 10 ° C. or higher has less chip standing and voids compared to those having a difference in alloy peak temperature of less than 10 ° C. There are also few solder balls.
FIG. 3 shows a solder alloy mixture in which 65% of the first solder alloy powder (Sn-3.5Ag-12In-0.5Bi) and 35% of the second solder alloy powder (Sn-3.5Ag-0.5Bi) are mixed. is a graph showing a differential thermal analysis curve of the powder, since the first solder alloy powder and the second solder alloy respective peak temperatures P 1 of the powder, P 2 are sufficiently separated and 10 ° C. or higher, in fact first The liquidus temperature of the solder alloy powder and the solidus temperature of the second solder alloy powder do not overlap. Rather, the first and second solder alloy powders having a peak temperature difference of 10 ° C. or more are selected and combined to form a solder paste so as to be like that. The composition after melting was Sn-3.5Ag-8In-0.5Bi.
Needless to say, the Sn-Ag-In-based lead-free solder alloy of the present invention is effective not only for soldering chip components but also for fine pattern soldering.
以上説明したように耐熱性のない電子部品に使用可能だがリフロー時に発生するチップ立ちが多く使用しにくいＳｎ−Ａｇ−Ｉｎ系鉛フリーはんだ合金でも、本発明のソルダペーストを使えばリフロー時のチップ立ちおよびボイドが少なくなる。そのため安価な耐熱性のない電子部品が使用可能になり、本発明によりはんだの鉛フリー化が大きく前進するものである。 As described above, even if the solder paste of the present invention is used for the Sn-Ag-In lead-free solder alloy which can be used for electronic parts having no heat resistance but is difficult to use due to the chip standing generated at the time of reflow, the chip at the time of reflow is used. Standing and voids are reduced. Therefore, inexpensive electronic components without heat resistance can be used, and the lead-free solder is greatly advanced by the present invention.
Claims (4)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2004/003027 WO2005084877A1 (en) | 2004-03-09 | 2004-03-09 | Solder paste |
Publications (2)
| Publication Number | Publication Date |
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| JP3928657B2 true JP3928657B2 (en) | 2007-06-13 |
| JPWO2005084877A1 JPWO2005084877A1 (en) | 2007-08-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP2005518736A Expired - Lifetime JP3928657B2 (en) | 2004-03-09 | 2004-03-09 | Solder paste |
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| US (1) | US8961709B1 (en) |
| EP (1) | EP1724050B1 (en) |
| JP (1) | JP3928657B2 (en) |
| KR (1) | KR101052452B1 (en) |
| CN (1) | CN100503133C (en) |
| MY (1) | MY139434A (en) |
| TW (1) | TWI308510B (en) |
| WO (1) | WO2005084877A1 (en) |
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| JP5142999B2 (en) * | 2006-07-05 | 2013-02-13 | 富士電機株式会社 | Cream solder and soldering method for electronic parts |
| TWI481466B (en) * | 2009-03-30 | 2015-04-21 | Arakawa Chem Ind | Lead-free solder flux composition and lead-free solder composition |
| US8598464B2 (en) | 2009-04-20 | 2013-12-03 | Panasonic Corporation | Soldering material and electronic component assembly |
| CN104308388A (en) * | 2010-11-26 | 2015-01-28 | 深圳市晨日科技有限公司 | Die-bond soldering paste for high-power LED and preparation method of die-bond soldering paste |
| JP6272676B2 (en) * | 2013-11-07 | 2018-01-31 | 東レエンジニアリング株式会社 | Bonding equipment |
| JP5732627B2 (en) | 2013-11-27 | 2015-06-10 | パナソニックＩｐマネジメント株式会社 | Solder material and joint structure |
| JP6405920B2 (en) * | 2014-11-12 | 2018-10-17 | 千住金属工業株式会社 | Solder paste flux, solder paste and solder joint |
| JP5970091B2 (en) * | 2015-01-27 | 2016-08-17 | パナソニックＩｐマネジメント株式会社 | Manufacturing method of bonded structure |
| JP6332525B1 (en) * | 2017-05-25 | 2018-05-30 | 千住金属工業株式会社 | Solder paste |
| EP3708290B1 (en) * | 2018-04-13 | 2021-11-03 | Senju Metal Industry Co., Ltd | Solder paste |
| DE112019005431T5 (en) * | 2018-10-31 | 2021-07-15 | Robert Bosch Gmbh | MIXED ALLOY SOLDER PASTE, METHOD OF PRODUCING THE SAME AND SOLDERING METHOD |
| US11267080B2 (en) | 2019-05-09 | 2022-03-08 | Indium Corporation | Low temperature melting and mid temperature melting lead-free solder paste with mixed solder alloy powders |
| CN110153589B (en) * | 2019-06-17 | 2021-05-11 | 常熟理工学院 | A kind of indium-based solder and preparation method thereof |
| US20230241725A1 (en) * | 2022-01-19 | 2023-08-03 | Ning-Cheng Lee | Solder pastes and methods of using the same |
| WO2025243792A1 (en) * | 2024-05-24 | 2025-11-27 | 千住金属工業株式会社 | Solder paste and method for producing joined body |
| WO2025243793A1 (en) * | 2024-05-24 | 2025-11-27 | 千住金属工業株式会社 | Solder paste and method for producing joined body |
| CN119016833B (en) * | 2024-10-18 | 2025-03-11 | 天合光能股份有限公司 | Solar cell welding method and solar cell |
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| JPH01241395A (en) * | 1988-03-19 | 1989-09-26 | Matsuo Handa Kk | Cream solder |
| JPH01266987A (en) * | 1988-04-19 | 1989-10-24 | Senju Metal Ind Co Ltd | Creamy solder and its soldering method |
| JPH01271094A (en) * | 1988-04-20 | 1989-10-30 | Aiwa Co Ltd | Paste-like solder |
| JPH02211995A (en) * | 1989-02-10 | 1990-08-23 | Aiwa Co Ltd | Pasty solder |
| US5256370B1 (en) * | 1992-05-04 | 1996-09-03 | Indium Corp America | Lead-free alloy containing tin silver and indium |
| JPH0653645A (en) * | 1992-07-17 | 1994-02-25 | Matsushita Electric Ind Co Ltd | Reflow soldering method |
| US5573602A (en) * | 1994-12-19 | 1996-11-12 | Motorola, Inc. | Solder paste |
| EP0834376A4 (en) * | 1995-06-20 | 2003-01-22 | Matsushita Electric Industrial Co Ltd | SOLDER, SOLDERED ELECTRONIC PART AND ELECTRONIC BOARD |
| JP3220635B2 (en) * | 1996-02-09 | 2001-10-22 | 松下電器産業株式会社 | Solder alloy and cream solder |
| JPH09277082A (en) | 1996-04-17 | 1997-10-28 | Senju Metal Ind Co Ltd | Solder paste |
| JPH11186712A (en) | 1997-12-24 | 1999-07-09 | Nissan Motor Co Ltd | Solder paste and connection method |
| JPH11347784A (en) * | 1998-06-01 | 1999-12-21 | Victor Co Of Japan Ltd | Soldering paste and electronic circuit using the same |
| JP2000052082A (en) * | 1998-08-07 | 2000-02-22 | Senju Metal Ind Co Ltd | Solder paste for chip parts |
| GB9903552D0 (en) * | 1999-02-16 | 1999-04-07 | Multicore Solders Ltd | Reflow peak temperature reduction of solder alloys |
| JP3753168B2 (en) | 1999-08-20 | 2006-03-08 | 千住金属工業株式会社 | Solder paste for joining microchip components |
| SG98429A1 (en) * | 1999-10-12 | 2003-09-19 | Singapore Asahi Chemical & Solder Ind Pte Ltd | Lead-free solders |
| JP4438974B2 (en) | 2000-10-05 | 2010-03-24 | 千住金属工業株式会社 | Solder paste |
| JP2002120085A (en) * | 2000-10-12 | 2002-04-23 | H Technol Group Inc | Lead-free solder alloy |
| JP3763520B2 (en) | 2000-12-25 | 2006-04-05 | Ｔｄｋ株式会社 | Soldering composition |
| SG139507A1 (en) * | 2001-07-09 | 2008-02-29 | Quantum Chem Tech Singapore | Improvements in or relating to solders |
| AU2003299955A1 (en) * | 2002-12-31 | 2004-07-29 | Motorola, Inc | Mixed alloy lead-free solder paste |
| JP4613823B2 (en) * | 2003-04-01 | 2011-01-19 | 千住金属工業株式会社 | Solder paste and printed circuit board |
-
2004
- 2004-03-09 EP EP04718726.5A patent/EP1724050B1/en not_active Expired - Lifetime
- 2004-03-09 KR KR1020067016859A patent/KR101052452B1/en not_active Expired - Lifetime
- 2004-03-09 US US10/588,647 patent/US8961709B1/en active Active
- 2004-03-09 WO PCT/JP2004/003027 patent/WO2005084877A1/en not_active Ceased
- 2004-03-09 JP JP2005518736A patent/JP3928657B2/en not_active Expired - Lifetime
- 2004-03-09 CN CNB2004800423053A patent/CN100503133C/en not_active Expired - Lifetime
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Also Published As
| Publication number | Publication date |
|---|---|
| CN1925946A (en) | 2007-03-07 |
| EP1724050A1 (en) | 2006-11-22 |
| CN100503133C (en) | 2009-06-24 |
| EP1724050A4 (en) | 2009-06-03 |
| MY139434A (en) | 2009-09-30 |
| TW200538226A (en) | 2005-12-01 |
| TWI308510B (en) | 2009-04-11 |
| EP1724050B1 (en) | 2013-12-04 |
| JPWO2005084877A1 (en) | 2007-08-30 |
| KR20060131848A (en) | 2006-12-20 |
| KR101052452B1 (en) | 2011-07-28 |
| WO2005084877A1 (en) | 2005-09-15 |
| US8961709B1 (en) | 2015-02-24 |
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